Record-plate for gramophones.



PATENTED MAY 24,1904; T. B.BI;RNBAUM1 k RECORD PLATE FOR GRAMOPHONES.

Patented May 24, 1904.

PATENT OFFICE.

THEODORE B. BIRNBAUM, OF BERLIN, GERMANY.

RECORD-PLATE FOR GRAMOPHO NES SPECIFICATION forming part of LettersPatent No. 760,606, dated May 24, 1904. Application filed December24,1900. Serial No". 40,947. 1N0 modell) I To all whom it may concern:

Be it known that I, THEODORE B. BIRNBAUM, managing director, a subjectof the Queen of Great Britain and Ireland, residing at 36 Ritterstrasse,in the city of Berlin, in the German Empire, have invented certain newand useful Improvements in Record-Plates for Gramophones, of which thefollowing isa specification.

The record-plates for gramophones are made of circular disks of hardrubber or similar material of about one-tenth inch thickness.

These plates ortablets are, as a rule, fitted with an aperture for thereception of the rotating shaft when the gramophone is placed Upon thesurface of the record-tablet the phonographic record-line is engraved,forming a spiral-like groove, serving to guide the gramophone-needlewhich is connected to the sounding-drum. Upon the rotation of therecord-tablet the needle moves in the spiral-like groove from the edgeof the tablet to the center thereof, corresponding to. the configurationand the extent of the said.

spiral groove. The commencing point of the record-line is accordinglyarranged near the periphery of the tablet about one-fifth of an inchfrom its outer edge. With this form of arrangement of gramophonerecord-tablets it is a great inconvenience that it requres a certainamount of skill to introduce the needle into the outer extremity of therecord-line, a very serious drawback, which is especially troublesome ifshort-sighted persons want to make use of the gramophone. Furthermore,it frequently happens, unless great care is taken in positioning theneedle upon the record-tablet, that the needle glides off the edge ofthe said tablet and strikes against the driving-gear of the contrivance,whereby the neewhi ch projects about one twenty-fifth to onetenth of aninch upon the upper surface of the said tablet. The spirally-woundrecordline is so arranged upon the record-tablet as to start directly atthe projecting edge I) or in the proximity thereof. To start thegramophone, it is only necessary toplace the point of the needle closeto the projecting rim 6 of the plate (0. Thus it is possible to operatethe gramophone even in a dark room and without the necessity of specialskillor experience in handling, inasmuch as the touch will afford asufiicient guide to the operator for the adjustment of the needle uponthe gramophone-tablet in the proper position for actuating theapparatus. The projecting rim presents the further advantage of a farmore eflicient ,protection'against' injury from exterior influences ofthe upper part of the tablet, which contains the spirally-woundrecordline. If a number of record-tablets construct ed according to myinvention are placed on top of each other, the tablet bearing the rec.-ord-groove is not touched at all by the upper tablet in view of thelatter resting upon the rim 6 of the lower tablet or plate Then thethick edge affords a greater security against breakage, and thus rendersthe tablet more durable.

What I claim, and desire to secure by Letters Patent of the UnitedStates, is-

A flat gramophone-plate provided with an integral annular rim projectingabove its record-surface atthe extreme outer edge of the platev and thesaid surface having a spirallyarranged record-line formed therein,saidline beginning close to the inner side of said rim and terminating at apoint remote from the rim near the center, said rim being adapted toguide the gramophone-needle into'the beginning of the record-line,substantially as set forth.

In witness whereof I have hereunto signed my. name in the presence oftwo subscribing Witnesses.

THEODORE B. BIRNBAUM.

Witnesses:

HENRY HASPER, VVoLDEMAR HAU'P'I.

